Battery System Monitor by
TriMetric MODEL 2020
Main Data Functions
SELECT to cycle through these functions:
Volts: Reads 8.0 - 35.0 volts accurate to �.08 volt including"digit
resolution" accuracy. An optional adapter extends this to 70 volts for 32 or 48V
systems and delivers lightning protection too. Please see accessory section for
Amps: Measures amps into and out of battery, accurate to �1%�1 least
significant digit. Or the meter may be set up to measure only incoming amps from
solar array or other energy source, or only load amps if desired. Resolution and
maximum amps depends on choice of shunt. With the 100A/100mV shunt: measures
0.01 to 250 amps. With 500A/50mV shunt: measures from 0.1 to 1000 amps. Shunt
type is programmable, so amps always display correctly. Speed of response one
second time constant.
Percent Full: This number is based on net-amp hour reading divided by the
user programmable value of battery capacity. This is more reliable than other
methods which do not use amp hours to compute battery energy content (for
example less expensive monitors which rely only on battery voltage to estimate
There is a
(user programmable) choice of two ways to display this result:
literal reading from 0-100% in increments of 1%,
"accurate" display which shows in steps of 5%, and displays "FUL" when above
92%, and "LO" when below 27%. Although the meter amp hour measurement accuracy
is ~1%, this option is intended to reflect the fact that the system accuracy
in determining how much energy content in an actual battery system, (assuming
the batteries are recharged fully at least every week) is more honestly stated
as ~5%. The assumed BATTERY CAPACITY, upon which this display is based, can be
programmed from 10-2550 amp hours, in increments of 10 amp hours.
The display may be turned off (for lowest current draw of 16 ma.)
TriMetric senses that batteries are charged: it resets the "days since
charged" display to 0.00 and (at user option) resets the "amp hours" to 0.00 and
the "Battery % Full" to 100%. The TriMetric determines that the batteries are
"charged" when the battery voltage rises above a user programmed "charged
voltage" (adjustable from 10.0-35.0 volts within 0.1 volt) and the charging amps
goes below a user programmable "charge current criteria" (adjustable from 1-100
amps within 1 amp). This condition must remain for 20 seconds.
Selectable Efficiency Factor: Amp hours may be monitored without an
"efficiency factor," meaning that the "charge" and "discharge" current for the
"net amp hours" reading are both accumulated at exactly 100% rate. Or a "charge
efficiency" factor may be manually set from 60% to 100% in 1% increments. This
means that the discharging current will subtract from amp hours at 100% rate,
where as the charging current accumulates at the lower specified rate, to
approximate the "charge efficiency" of the battery. This compensates for the
fact that you don't get quite as much charge out of a battery as you put in.
Proven Measurement Circuit: This TriMetric circuit has proven accurate and
reliable for over three years in production. All programmed information retained
when meter unpowered.
Locatable: Up to 55 feet with four #22 ga. wires. Up to 150 feet with #18
wire. Longer distances are possible with larger wire size.
Display With Low Current Draw: Requires about 30mA with display on-about
16mA with display off.
Designed to fit into a standard "double-gang" electrical box mounted 90 degrees
from the usual position. See accessories section (on the back) for suitable
enclosure. Panel size ( inches): 41/2 x 43/4 x 13/4 deep .
button down for two seconds, release, then push
SELECT again to cycle through these six
functions. The data alternates with identifier letters which are shown on front
Hours From "Full": Shows actual "net" amp hours removed from the battery from
±0.01 to ±9,999 amp hours. A flashing decimal point reminds you to multiply
the reading by 1000 when the amp hour number exceeds 999. May be manually set
to 0, or automatically when the "charged" criteria are met. (See information
below on "How TriMetric determines that batteries are charged"). It is also
possible for this display to measure only total amp hours produced by an
energy source, such as solar array, or only load amp hours, by wiring the
shunt in the desired current path.
Many Days Ago Since Batteries Were Last Fully Charged: To prolong their life,
lead-acid batteries shouldn't go too long between being fully charged. This
display will show you how long since they last received a full charge-measures
from 0.01 day to over 600 days. It's a timer that resets to 0.00 whenever
batteries are fully charged (i.e. meets charged criteria as described below).
If desired the "battery reminders" lamp will alert the user when this number
exceeds a value programmable by user from 1 to 60 days. May also be manually
reset with the "reset" button.
Many Days Ago Since The Battery Was Equalized: "Wet cell" lead acid batteries
should be periodically given an overcharge, called "equalization," to maintain
their capacity. This is typically done every month or two. It's easy to forget
when they were last equalized-this timer will keep track for you. Reads from
0.01 day to over 600 days. You will need to reset this number manually
whenever you equalize the batteries. In addition, if desired the "battery
reminders" lamp will alert you when this number exceeds a user adjustable
"maximum equalize time" from 1-250 days.
Cumulative Battery Amp Hours: Records only discharging amp hours-displays to
minus one million amp hours. (A flashing decimal point in the display tells
you to multiply the reading by 1000). This function acts like an odometer in a
car, to show how much total chemical change the battery has seen in its life.
It's a "bottom line" number of total battery endurance and can be used to
evaluate the life performance of the batteries and the care they've received
at time of replacement of the battery set. This number stays in the TriMetric
even if power is disconnected-in that case a maximum of the last 3.2 hours of
data will be lost. When replacing the battery set the number to 0 by pushing
"reset" button while this display is showing.
Maximum Battery Volts: Useful to check that the charging sources are charging
to the voltage recommended by battery manufacture for longest life. Pushing
the "reset" button when displayed to reset this display to the present battery
Minimum Battery Volts: Use this to check that batteries haven't been over
discharged. Pushing the "reset" button when displayed to reset this display to
the present battery voltage.